Recent content by Taz99

I would make sure that you have looked at the mode shape of the buckling mode with the negative eigen vector that you have mentioned and see what part of the structure is buckling (it could be the circumferential flange as opposed to the walls). In your static analysis you should see whatever...

You can have a look at what Airborne are doing with RTP pipes. For some short words on their qualification approach check out http://www.airborneinternational.com/index.php?option=com_content&view=article&id=115:qualification&page=detail&catid=34:oil-a-gas&Itemid=2 "Because no specific (ISO...

thanks, this makes sense to me "it is not realistic to have the fastener carry both the entire preload and shear load."

Thanks for the reply, but accounting for pre-load doesn't seem to match with the actual stress analysis practices in industry. I have looked at Bhrun, Flabel and HSB 20210 and none make any mention of requiring you to consider the bolt pre-load in the bolt shear-tension interaction calculation...

Hi All, When considering steel bolt shear and tension interaction failure I use the Rt2 +Rs3 < 1 failure criterion. Where Rs and Rt are the ratio applied load / allowable load in shear and tension. I have never considered the pre-tension load in the bolt in this calculation. Recently the...

Thanks for the response, from the ASIC site I found "Specification for Structural Joints Using High-Strength Bolts" which mentions knockdown factor of 0.75 on the nominal bolt strength, so I have this answered. The clamp is intended for above ground operations, so no wave loads, only internal...

Hi All, I usually work on Aerospace projects but have ended up sizing a new Stand Off Clamp design and wanted to run a few things past the group. I have been advised by the customer of an pipeline operating pressure that they wish to be able to claim, they have advised that we should apply a...

Great thanks for the replies, we have decided to go ahead with the socket head bolt plus a washer.

Hi All, I have a (non aerospace) installation where due to a lack of access I was considering using either a socket head bolt or 12 point head bolt and I would apply the torque from the head side while holding the nut fixed with a custom made tool. I think you would usually apply the torque...

Q) Is this the same force for the case I present (image '1' & '2')? A) No - For a stretch forming operation the vertical load from your hydraulic ram will be reacted by tensile membrane loads within the plane of the Al sheet (think along the lines of a drop of water supported by a stretched...

got it now - thanks!

Often you will see in articles the author stating that a FE model has xxx DOF to indicate how long it may take to run or to convey approximately how big the model is. Could someone explain how I can get the number of DOF from either Patran or from Nastran output files? Thanks :)

Some Australian Sea King Helicopters flew with cracks in main gearbox mounting feet. Flight envelope was limited to "pilot shall feel no appreciable g's" lol

What I think you are trying to do is account for the effect of either a stress concentration, or a stress gradient due to a bending moment to reduce a peak stress shown in your FE model. However, I think you have to be careful with taking a single stress strain pair and using the approach you...

Jeram you should get matching positive and negative eigenvalues when the model and loading has a plane of symmetry, as your model does. I would guess that the negative eigenvalue is slightly more critical than the positive one and that is why it is listed as the first eigenvalue. Your...